Infrared
4 marks · NormalDescribe an experiment you could perform to compare how different surfaces (e.g. shiny metal vs. matt black) emit infrared radiation when heated.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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Must show: Heat both surfaces equally, Use identical objects with different finishes, Use infrared detector or thermometer at equal distance, Compare rate/amount of cooling or emission recorded
Common mistakes: No control of variables; Only describing absorption, not emission
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Mentions heating both surfaces equally (fair test).
M2 · 1 mark · States that objects should be identical except for surface finish.
M3 · 1 mark · Describes using an infrared detector/thermometer at the same distance or location.
A1 · 1 mark · States that readings are compared to determine which surface emits more infrared (e.g., cools faster, emits more).
Worked solution
Take two metal cans—one painted black and one with a shiny metal surface. Heat both cans to the same temperature using hot water. Place an infrared detector or a thermometer next to each can at the same distance. Record the rate at which each can cools down or the infrared detected. The can that loses heat faster (or has a higher infrared emission) is emitting more infrared radiation.